I use CUDA for finance based Monte-Carlo simulations. Unless you are at a place with a huge cluster that you have access to, some problems cannot be solved without CUDA.
One downside to CUDA is its massively powerful for single FP precision, but double FP precision performance is less than 1/10 of single FP performance.
When precision is needed CUDA is much less useful, say you're running 10^10 simulations then with single FP precision you will only have a result accurate to 5 significant figures.
